THE CARTOGRAPHIC DATA IMPORTANCE IN THE HYDROLOGICAL AND HYDRAULIC STUDIES: THE CASE OF MANHUAçU CATCHMENT, MINAS GERAIS, BRAZIL

L.S. Santos, C.Jr. Bielenki, N.O. Nascimento

UFMG

lucasbrasil@ehr.ufmg.br

The objective of this paper is to demonstrate the importance of the cartographic data as input data for the hydrological simulation and the strict relationship with the quality reached in the simulation. Different processes were evaluated for data acquisition and the importance of the generated products, as well as the remote sensor data integration.

For the first evaluation of topography study area a terrain digital model has been done with the data from the Shuttle Radar Topography Mission (SRTM 90). A cartographic base from the systematic cartography supplied by the Brazilian Institute of Geography and Statistics (IBGE) and from the Brazilian Army Geographical Service (DSG) was used to digitalize altimetric data. With this last data, a digital model was also generated. Altimetric and slope profiles of the main rivers of the studied area are examples of derived data extracted from the cartographic for input data in the hydrological simulation. Besides, the cartographic data supplied the acquisition of soil covering of the study area. Quantitative and qualitative parameters for the estimation of area permeability index have been acquired.

The methodology used for the basic hydrological and hydraulic parameters acquisition was applied in the Manhuaçu river basin, located in the Minas Gerais state, Brazil. The Manhuaçu catchment, with an area of 593 km², is predominantly occupied by natural forest and agricultural activities (18% of the area). Occupation by urban areas, essentially the town of Manhuaçu, represents only 1% of the total catchment area. The Manhuaçu catchment is characterized by steep slopes and a dense network of streams flowing along narrow valleys.

The hydrologic and hydraulic modeling of historic and design events with a detailed survey allowed: to get a sound understanding of the hydrologic processes at the catchment scale which influence the generation and frequency of flooding in the urban area; the identification and mapping of key areas at risk for flooding and its vulnerability and the evaluation of different flood control measures scenarios, associated or not with the adoption of intensive structural measures (e.g.: reservoirs).